How to Care for Agapanthus in the Garden

Lily of the Nile blooms are blue, purple or white.

Agapanthus (Agapanthus spp.) provide large, exotic flowers to enhance early through mid-summer garden displays. The common name for Agapanthus is lily of the Nile, and there are many varieties of this perennial plant, some evergreen and some deciduous. Lily of the Nile grows well in containers, and the restricted root zone of containerized plants seems to encourage flowering. Most varieties grow in U.S. Department of Agriculture plant hardiness zones 8 through 10, and a few grow in USDA zones 6 and 7 through 10. Care involves feeding plants to promote blooming and boost growth after flowering.

Feeding In-Ground and Containerized Plants

Feeding lily of the Nile in spring and late summer encourages the plant to flower well. To feed an in-ground lily of the Nile, spread a ready-to-use, slow-release granular 12-4-8 fertilizer at a rate of 4 tablespoons per 4 square feet around the plant when it begins growing in spring. Feed a potted lily of the Nile at the same time, applying 3 tablespoons of fertilizer to a 12-inch container or 5 tablespoons of fertilizer to a 14-inch container. Sprinkle the granules evenly over the soil surface, avoiding the plant stems. Fertilize lily of the Nile with the same product at the same rates after the last flowers have faded. Manufacturer's instructions can vary, so always apply fertilizers according to the product label.

Watering Lily of the Nile

Water needs for lily of the Nile vary according to the season. When the plant is actively growing, lily of the Nile needs water whenever the soil surface is dry to a depth of 1 inch in containers or around in-ground plants. Containers for lily of the Nile must have drainage holes. Water a potted plant until water runs through the drainage holes, and leave it to drain before returning the container to its drip tray. Water an in-ground lily of the Nile thoroughly, but stop watering when the water starts to puddle around the plant. Lily of the Nile needs very little water over winter because it stops growing. Water potted evergreen plants enough to prevent the leaves from wilting, and keep potted deciduous plants just moist 2 to 3 inches below the soil surface. In-ground evergreen and deciduous plants rarely need water over winter.

Pruning Plants

Pruning lily of the Nile helps keep plants looking tidy. Wipe the blades of pruning shears with rubbing alcohol, and prune flower stems as the flowers fade, cutting the stems at their bases. Prune damaged leaves on evergreen and deciduous plants, and remove yellowing and dead leaves from deciduous plants in fall. Put lily of the Nile prunings on a compost pile or in the trash. Sterilize the pruning shear blades again when you've finished to avoid risk of transferring pests or diseases to other plants.

Protecting Lily of the Nile

In USDA zone 8, lily of the Nile needs protection from cold snaps. Potted plants should be placed in a frost-free indoor area if weather forecasts predict temperatures below 15 degrees Fahrenheit. Place evergreen varieties in a bright area out of direct sunlight and place deciduous varieties in an out of the way, cool, dry place. To protect in-ground evergreen and deciduous plants from cold weather, spread a 5- to 6-inch layer of straw over the root zone. Place baskets over the plants to hold the mulch in place and to protect the leaves of evergreen plants. Remove the mulch and covering from in-ground plants and place potted plants outside when the weather warms up. Lily of the Nile rarely suffers from serious pests or diseases.